Convenient and practical jQuery checkbox checkbox select all function simple example_jquery

// Main checkbox
// Sub-checkbox item

var $ckAll = $("input[name=' ckAll']");
var $ckItm = $("input[name='ckItm']");
var len = $ckItm.length;
$ckAll.click(function() {
// Get the current selected status of $ckAll. If selected, other sub-checkboxes will be selected, otherwise they will be cancelled.
$ckItm.prop('checked',this.checked);
});
$ckItm.click(function() {
// Bind the judgment event to b
var b=$ckItm.filter(":checked").length==len;// When the selected The number of sub-checkboxes is equal to the total number, and the main checkbox will be selected
// Determine through ternary operation
var flag=$ckAll.prop("checked",b?true:false) ;
});